About a third of campus buildings were without power beginning at about 3 p.m. on Wednesday.

Power was restored by Land, Buildings &Real Estate (LBRE) staff members to all but eight buildings by about 7:30 p.m.  LBRE staff will be working overnight to identify the source of the problem and plan to provide an update on emergency.stanford.edu in the morning.

The exact cause of the fault – meaning the interruption in power – was still underdetermined late Wednesday evening.

Sixty-seven buildings were affected by the power outage, ranging from athletics facilities on the east side of campus to parts of the School of Medicine on the west side. In between, a plethora of buildings had no power or were running on back-up generators, including the Arrillaga Alumni Center, the Graduate School of Business campus, the Sapp Center for Science Teaching and Learning and the Clark Center.

No student residences or dining facilities were affected. Evening classes were canceled in affected buildings. Plans were being formulated should classes need to be canceled or relocated for Wednesday morning.

As the outage persisted throughout the afternoon and evening on Wednesday, Environmental Health & Safety officials recommended out of an abundance of caution that lab researchers in affected buildings cease work with hazardous materials, citing concerns about ventilation systems. Warnings were also issued that network and voice services could be lost as battery backups ran out.

Additional illumination was installed in areas where lighting was affected, including the intersection of Campus Drive and Roth Way. Department of Public Safety personnel were also dispatched to streets where bollards were not working.

At around 5:30 p.m., LBRE workers began slowly and methodically testing individual circuits throughout campus, searching for the cause of the power outage. By around 7:30 p.m., all but eight major buildings had power restored. Those buildings included Psychiatry Academic and Clinical, the Anderson Collection, Roth Way garage, Mudd Chemistry, Stauffer I and II, Gilbert Biology, portions of the Paul Allen Building and Chemistry Conference Center.

LBRE continued working throughout the evening to identify the fault on a line called “Feeder #5,” which is about 2 miles long. LBRE estimated that finding the specific fault in that line could take up to eight hours. Fixing the fault could take much longer.

For more information and further updates, visit emergency.stanford.edu .